Re: Router stops routing after changing MAC Address
On Mon, Mar 13, 2006 at 10:00:41AM -0800, Stephen Hemminger wrote: There still is a bug in the 3c59x driver. It doesn't include any code to handle changing the mac address. It will work if you take the device down, change address, then bring it up. But you shouldn't have to do that. I sent a patch do to this probably a year or two back and it was rejected (by akpm if I recall) because of the argument that you could and should take it down, change the MAC and bring it back up. Is this no longer a requirement? - To unsubscribe from this list: send the line unsubscribe netdev in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: Router stops routing after changing MAC Address
On Thu, 16 Mar 2006 08:07:43 -0800 Chris Wedgwood [EMAIL PROTECTED] wrote: On Mon, Mar 13, 2006 at 10:00:41AM -0800, Stephen Hemminger wrote: There still is a bug in the 3c59x driver. It doesn't include any code to handle changing the mac address. It will work if you take the device down, change address, then bring it up. But you shouldn't have to do that. I sent a patch do to this probably a year or two back and it was rejected (by akpm if I recall) because of the argument that you could and should take it down, change the MAC and bring it back up. Is this no longer a requirement? No. most drivers allow changes on the fly. - To unsubscribe from this list: send the line unsubscribe netdev in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
RE: Router stops routing after changing MAC Address
I wonder if they would be more open to accepting that patch now? - Greg Scott -Original Message- From: Stephen Hemminger [mailto:[EMAIL PROTECTED] Sent: Thursday, March 16, 2006 11:55 AM To: Chris Wedgwood Cc: Greg Scott; Chuck Ebbert; linux-kernel; David S. Miller; netdev@vger.kernel.org; Bart Samwel; Alan Cox; Simon Mackinlay Subject: Re: Router stops routing after changing MAC Address On Thu, 16 Mar 2006 08:07:43 -0800 Chris Wedgwood [EMAIL PROTECTED] wrote: On Mon, Mar 13, 2006 at 10:00:41AM -0800, Stephen Hemminger wrote: There still is a bug in the 3c59x driver. It doesn't include any code to handle changing the mac address. It will work if you take the device down, change address, then bring it up. But you shouldn't have to do that. I sent a patch do to this probably a year or two back and it was rejected (by akpm if I recall) because of the argument that you could and should take it down, change the MAC and bring it back up. Is this no longer a requirement? No. most drivers allow changes on the fly. - To unsubscribe from this list: send the line unsubscribe netdev in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: Router stops routing after changing MAC Address
linux-os (Dick Johnson) wrote: On Mon, 13 Mar 2006, Greg Scott wrote: Bst... Not! There are not any MAC addresses associated with any of the intercity links, usually not even in WANs! MAC is for Ethernet! Once you go to fiber, ATM, T-N, etc., there are no MAC addresses. Bt. According to WikiPedia: http://en.wikipedia.org/wiki/MAC_address MAC addresses are used for: - Token ring - 802.11 wireless networks - Bluetooth - FDDI - ATM (switched virtual connections only, as part of an NSAP address) - SCSI and Fibre Channel (as part of a World Wide Name) FDDI = fiber, ATM = ATM. --Bart - To unsubscribe from this list: send the line unsubscribe netdev in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: Router stops routing after changing MAC Address
Bt. According to WikiPedia: http://en.wikipedia.org/wiki/MAC_address MAC addresses are used for: - Token ring - 802.11 wireless networks - Bluetooth - FDDI - ATM (switched virtual connections only, as part of an NSAP address) - SCSI and Fibre Channel (as part of a World Wide Name) FDDI = fiber, ATM = ATM. http://developer.intel.com/design/network/products/optical/framers/ixf18104.htm It works too. Cheers, Simon -- ___ Play 100s of games for FREE! http://games.mail.com/ - To unsubscribe from this list: send the line unsubscribe netdev in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: Router stops routing after changing MAC Address
On Tue, 14 Mar 2006, Bart Samwel wrote: linux-os (Dick Johnson) wrote: On Mon, 13 Mar 2006, Greg Scott wrote: Bst... Not! There are not any MAC addresses associated with any of the intercity links, usually not even in WANs! MAC is for Ethernet! Once you go to fiber, ATM, T-N, etc., there are no MAC addresses. Bt. According to WikiPedia: http://en.wikipedia.org/wiki/MAC_address MAC addresses are used for: - Token ring - 802.11 wireless networks - Bluetooth - FDDI - ATM (switched virtual connections only, as part of an NSAP address) - SCSI and Fibre Channel (as part of a World Wide Name) FDDI = fiber, ATM = ATM. --Bart A name is NOT. I can call my mail route number RFD#2 a MAC address. Also token-ring is a form of Ethernet as are all known wireless networks unless they use light. Even cable modems use Ethernet, with FDM on the cable side and baseband on the customer side. Calling SCSI MAC is absurd. All of the above, except the ethernets are forms of point-to-point communications links. IP (over/under or through) these links uses a source and destination IP and any hardware addressing scheme is incidental. Cheers, Dick Johnson Penguin : Linux version 2.6.15.4 on an i686 machine (5589.54 BogoMips). Warning : 98.36% of all statistics are fiction, book release in April. _ The information transmitted in this message is confidential and may be privileged. Any review, retransmission, dissemination, or other use of this information by persons or entities other than the intended recipient is prohibited. If you are not the intended recipient, please notify Analogic Corporation immediately - by replying to this message or by sending an email to [EMAIL PROTECTED] - and destroy all copies of this information, including any attachments, without reading or disclosing them. Thank you. - To unsubscribe from this list: send the line unsubscribe netdev in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
RE: Router stops routing after changing MAC Address
Yet I have real-world examples I've seen with my own eyes where MAC Address problems have messed up bridged networks. I posted some of those here yesterday. Good old Ethernet MAC Addresses can and do play a real role in these wide area networks. Don't believe me? Try it yourself. Find a LAN connected to the Internet via bridged DSL or cablemodem with a real firewall in place. Swap the firewall and wait...and wait...and wait some more for ARP caches to clear on the other end. When nothing changes but the passage of time and traffic starts to flow again - and the Internet service is bridged not routed - give me another explanation besides ARP caches. - Greg -Original Message- From: linux-os (Dick Johnson) [mailto:[EMAIL PROTECTED] Sent: Tuesday, March 14, 2006 6:53 AM To: Bart Samwel Cc: Greg Scott; Rick Jones; Chuck Ebbert; linux-kernel; netdev@vger.kernel.org; Alan Cox; Simon Mackinlay Subject: Re: Router stops routing after changing MAC Address On Tue, 14 Mar 2006, Bart Samwel wrote: linux-os (Dick Johnson) wrote: On Mon, 13 Mar 2006, Greg Scott wrote: Bst... Not! There are not any MAC addresses associated with any of the intercity links, usually not even in WANs! MAC is for Ethernet! Once you go to fiber, ATM, T-N, etc., there are no MAC addresses. Bt. According to WikiPedia: http://en.wikipedia.org/wiki/MAC_address MAC addresses are used for: - Token ring - 802.11 wireless networks - Bluetooth - FDDI - ATM (switched virtual connections only, as part of an NSAP address) - SCSI and Fibre Channel (as part of a World Wide Name) FDDI = fiber, ATM = ATM. --Bart A name is NOT. I can call my mail route number RFD#2 a MAC address. Also token-ring is a form of Ethernet as are all known wireless networks unless they use light. Even cable modems use Ethernet, with FDM on the cable side and baseband on the customer side. Calling SCSI MAC is absurd. All of the above, except the ethernets are forms of point-to-point communications links. IP (over/under or through) these links uses a source and destination IP and any hardware addressing scheme is incidental. Cheers, Dick Johnson Penguin : Linux version 2.6.15.4 on an i686 machine (5589.54 BogoMips). Warning : 98.36% of all statistics are fiction, book release in April. _ The information transmitted in this message is confidential and may be privileged. Any review, retransmission, dissemination, or other use of this information by persons or entities other than the intended recipient is prohibited. If you are not the intended recipient, please notify Analogic Corporation immediately - by replying to this message or by sending an email to [EMAIL PROTECTED] - and destroy all copies of this information, including any attachments, without reading or disclosing them. Thank you. - To unsubscribe from this list: send the line unsubscribe netdev in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: Router stops routing after changing MAC Address
On Mon, 13 Mar 2006 17:35:50 EST, linux-os (Dick Johnson) said: Bst... Not! There are not any MAC addresses associated with any of the intercity links, usually not even in WANs! MAC is for Ethernet! Once you go to fiber, ATM, T-N, etc., there are no MAC addresses. This will come as a big surprise to those places running Gig-E and 10G-E links into a fiber for long-haul cross-country connectivity. pgpO89beRHvTt.pgp Description: PGP signature
RE: Router stops routing after changing MAC Address
On eth0 - no. My fudged MAC Address is based on the IP Address. So 1.2.3.50 becomes 001.002.003.050, which turns into 00:10:02:00:30:50. But 1.2.3 is fake - it isn't the one I really use. The other one, 172.16.16.3 - that is a real IP Address that turns into 17:20:16:01:60:03. And here I thought I was pretty clever - it never dawned on me in my wildest dreams that those bits had any special meaning! I will do some homework about what all the bits mean and then put together another scheme for my fudged IP Addresses and post the results here. - Greg -Original Message- From: Chuck Ebbert [mailto:[EMAIL PROTECTED] Sent: Monday, March 13, 2006 12:11 AM To: Greg Scott Cc: linux-kernel; David S. Miller Subject: Re: Router stops routing after changing MAC Address In-Reply-To: [EMAIL PROTECTED] On Fri, 10 Mar 2006 18:33:15 -0600, Greg Scott wrote: How to change MAC addresses is documented well enough - and it works - but when I change MAC addresses, my router stops routing. From the router, I can see the systems on both sides - but the router just refuses to forward packets. Here are my little test scripts to change MAC Addresses. First - ip-fudge-mac.sh [EMAIL PROTECTED] gregs]# more ip-fudge-mac.sh ip link set eth0 down ip link set eth0 address 01:02:03:04:05:06 ^ Bit zero is set, so this is a multicast address. Is that intentional? ip link set eth0 up ip link set eth1 down ip link set eth1 address 17:20:16:01:60:03 ^ Ditto. ip link set eth1 up echo 1 /proc/sys/net/ipv4/ip_forward -- Chuck Penguins don't come from next door, they come from the Antarctic! - To unsubscribe from this list: send the line unsubscribe netdev in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
RE: Router stops routing after changing MAC Address
Message- From: Chuck Ebbert [mailto:[EMAIL PROTECTED] Sent: Monday, March 13, 2006 12:11 AM To: Greg Scott Cc: linux-kernel; David S. Miller Subject: Re: Router stops routing after changing MAC Address In-Reply-To: [EMAIL PROTECTED] On Fri, 10 Mar 2006 18:33:15 -0600, Greg Scott wrote: How to change MAC addresses is documented well enough - and it works - but when I change MAC addresses, my router stops routing. From the router, I can see the systems on both sides - but the router just refuses to forward packets. Here are my little test scripts to change MAC Addresses. First - ip-fudge-mac.sh [EMAIL PROTECTED] gregs]# more ip-fudge-mac.sh ip link set eth0 down ip link set eth0 address 01:02:03:04:05:06 ^ Bit zero is set, so this is a multicast address. Is that intentional? ip link set eth0 up ip link set eth1 down ip link set eth1 address 17:20:16:01:60:03 ^ Ditto. ip link set eth1 up echo 1 /proc/sys/net/ipv4/ip_forward -- Chuck Penguins don't come from next door, they come from the Antarctic! - To unsubscribe from this list: send the line unsubscribe netdev in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: Router stops routing after changing MAC Address
There still is a bug in the 3c59x driver. It doesn't include any code
to handle changing the mac address. It will work if you take the device
down, change address, then bring it up. But you shouldn't have to do that.
Also, if the driver handles setting mac address, it could have prevented
you from using a multicast address.
Something like this is needed (untested, I don't have that hardware).
--- linux-2.6/drivers/net/3c59x.c.orig 2006-03-13 09:58:25.0 -0800
+++ linux-2.6/drivers/net/3c59x.c 2006-03-13 09:52:47.0 -0800
@@ -895,6 +895,7 @@ static void dump_tx_ring(struct net_devi
static void update_stats(void __iomem *ioaddr, struct net_device *dev);
static struct net_device_stats *vortex_get_stats(struct net_device *dev);
static void set_rx_mode(struct net_device *dev);
+static int set_rx_address(struct net_device *dev, void *addr);
#ifdef CONFIG_PCI
static int vortex_ioctl(struct net_device *dev, struct ifreq *rq, int cmd);
#endif
@@ -1563,6 +1564,7 @@ static int __devinit vortex_probe1(struc
#endif
dev-ethtool_ops = vortex_ethtool_ops;
dev-set_multicast_list = set_rx_mode;
+ dev-set_mac_address = set_rx_address;
dev-tx_timeout = vortex_tx_timeout;
dev-watchdog_timeo = (watchdog * HZ) / 1000;
#ifdef CONFIG_NET_POLL_CONTROLLER
@@ -3150,6 +3152,27 @@ static void set_rx_mode(struct net_devic
iowrite16(new_mode, ioaddr + EL3_CMD);
}
+
+static int set_rx_address(struct net_device *dev, void *p)
+{
+ struct vortex_private *vp = netdev_priv(dev);
+ void __iomem *ioaddr = vp-ioaddr;
+ const struct sockaddr *addr = p;
+
+ if (!is_valid_ether_addr(addr-sa_data))
+ return -EADDRNOTAVAIL;
+
+ spin_lock_bh(vp-lock);
+ memcpy(dev-dev_addr, addr-sa_data, ETH_ALEN);
+
+ EL3WINDOW(2);
+ for (i = 0; i ETH_ALEN; i++)
+ iowrite8(dev-dev_addr[i], ioaddr + i);
+ spin_unlock_bh(vp-lock);
+
+ return 0;
+}
+
#if defined(CONFIG_VLAN_8021Q) || defined(CONFIG_VLAN_8021Q_MODULE)
/* Setup the card so that it can receive frames with an 802.1q VLAN tag.
Note that this must be done after each RxReset due to some backwards
-
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Re: Router stops routing after changing MAC Address
On Mon, 13 Mar 2006, Stephen Hemminger wrote:
There still is a bug in the 3c59x driver. It doesn't include any code
to handle changing the mac address. It will work if you take the device
down, change address, then bring it up. But you shouldn't have to do that.
Also, if the driver handles setting mac address, it could have prevented
you from using a multicast address.
Something like this is needed (untested, I don't have that hardware).
--- linux-2.6/drivers/net/3c59x.c.orig2006-03-13 09:58:25.0
-0800
+++ linux-2.6/drivers/net/3c59x.c 2006-03-13 09:52:47.0 -0800
@@ -895,6 +895,7 @@ static void dump_tx_ring(struct net_devi
static void update_stats(void __iomem *ioaddr, struct net_device *dev);
static struct net_device_stats *vortex_get_stats(struct net_device *dev);
static void set_rx_mode(struct net_device *dev);
+static int set_rx_address(struct net_device *dev, void *addr);
#ifdef CONFIG_PCI
static int vortex_ioctl(struct net_device *dev, struct ifreq *rq, int cmd);
#endif
@@ -1563,6 +1564,7 @@ static int __devinit vortex_probe1(struc
#endif
dev-ethtool_ops = vortex_ethtool_ops;
dev-set_multicast_list = set_rx_mode;
+ dev-set_mac_address = set_rx_address;
dev-tx_timeout = vortex_tx_timeout;
dev-watchdog_timeo = (watchdog * HZ) / 1000;
#ifdef CONFIG_NET_POLL_CONTROLLER
@@ -3150,6 +3152,27 @@ static void set_rx_mode(struct net_devic
iowrite16(new_mode, ioaddr + EL3_CMD);
}
+
+static int set_rx_address(struct net_device *dev, void *p)
+{
+ struct vortex_private *vp = netdev_priv(dev);
+ void __iomem *ioaddr = vp-ioaddr;
+ const struct sockaddr *addr = p;
+
+ if (!is_valid_ether_addr(addr-sa_data))
+ return -EADDRNOTAVAIL;
+
+ spin_lock_bh(vp-lock);
+ memcpy(dev-dev_addr, addr-sa_data, ETH_ALEN);
+
+ EL3WINDOW(2);
+ for (i = 0; i ETH_ALEN; i++)
+ iowrite8(dev-dev_addr[i], ioaddr + i);
+ spin_unlock_bh(vp-lock);
+
+ return 0;
+}
+
#if defined(CONFIG_VLAN_8021Q) || defined(CONFIG_VLAN_8021Q_MODULE)
/* Setup the card so that it can receive frames with an 802.1q VLAN tag.
Note that this must be done after each RxReset due to some backwards
-
Actually, it doesn't make any difference. Changing the IEEE station
(physical) address is not an allowed procedure even though hooks are
available in many drivers to do this. According to the IEEE 802
physical media specification, this 48-bit address must be unique and
must be one of a group assigned by IEEE. Failure to follow this
simple protocol can (will) cause an entire network to fail. If
you don't care, then you certainly don't care about multicast
bits either, basically let them set it to all ones as well.
Cheers,
Dick Johnson
Penguin : Linux version 2.6.15.4 on an i686 machine (5589.54 BogoMips).
Warning : 98.36% of all statistics are fiction, book release in April.
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RE: Router stops routing after changing MAC Address
But in a failover scenario you want two devices to have the same IEEE (station) Address (or MAC Address or hardware address). So many names for the same thing! When the primary unit fails, you want the backup unit to completely assume the failed unit's identity - right down to the MAC Address. The other way to do it using gratuitous ARPs is not good enough because some cheap router someplace with an ARP cache of several hours will not listen and will never update its own ARP cache. I like to think of this as bending the rules a little bit, not really breaking them. :) - Greg Actually, it doesn't make any difference. Changing the IEEE station (physical) address is not an allowed procedure even though hooks are available in many drivers to do this. According to the IEEE 802 physical media specification, this 48-bit address must be unique and must be one of a group assigned by IEEE. Failure to follow this simple protocol can (will) cause an entire network to fail. If you don't care, then you certainly don't care about multicast bits either, basically let them set it to all ones as well. Cheers, Dick Johnson Penguin : Linux version 2.6.15.4 on an i686 machine (5589.54 BogoMips). Warning : 98.36% of all statistics are fiction, book release in April. - To unsubscribe from this list: send the line unsubscribe netdev in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
RE: Router stops routing after changing MAC Address
On Mon, 13 Mar 2006, Greg Scott wrote: But in a failover scenario you want two devices to have the same IEEE (station) Address (or MAC Address or hardware address). So many names for the same thing! When the primary unit fails, you want the backup unit to completely assume the failed unit's identity - right down to the MAC Address. The other way to do it using gratuitous ARPs is not good enough because some cheap router someplace with an ARP cache of several hours will not listen and will never update its own ARP cache. I like to think of this as bending the rules a little bit, not really breaking them. :) - Greg Top posting, NotGood(tm). Anyway, if the device fails, you have routers and hosts ARPing the interface, trying to establish a route anyway. Actually, it doesn't make any difference. Changing the IEEE station (physical) address is not an allowed procedure even though hooks are available in many drivers to do this. According to the IEEE 802 physical media specification, this 48-bit address must be unique and must be one of a group assigned by IEEE. Failure to follow this simple protocol can (will) cause an entire network to fail. If you don't care, then you certainly don't care about multicast bits either, basically let them set it to all ones as well. Cheers, Dick Johnson Penguin : Linux version 2.6.15.4 on an i686 machine (5589.54 BogoMips). Warning : 98.36% of all statistics are fiction, book release in April. Cheers, Dick Johnson Penguin : Linux version 2.6.15.4 on an i686 machine (5589.54 BogoMips). Warning : 98.36% of all statistics are fiction, book release in April. _ The information transmitted in this message is confidential and may be privileged. Any review, retransmission, dissemination, or other use of this information by persons or entities other than the intended recipient is prohibited. If you are not the intended recipient, please notify Analogic Corporation immediately - by replying to this message or by sending an email to [EMAIL PROTECTED] - and destroy all copies of this information, including any attachments, without reading or disclosing them. Thank you. - To unsubscribe from this list: send the line unsubscribe netdev in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: Router stops routing after changing MAC Address
Anyway, if the device fails, you have routers and hosts ARPing the interface, trying to establish a route anyway. But only after what may be a much longer time than the customer is willing to accept or able to configure. I know of a number of HA situations where the new device is given the old MAC just to avoid that speicific situation of ARP caches not being updated except after quite some time. Not necessarily on the end-systems, the issue can be with intermediate devices (routers). And if one has to work with static ARP entries to deal (however imperfectly) with ARP poisioning or whatnot... Indeed, there is a large onus on the software doing the MAC override to make sure it does not break the required uniqueness. Just as if one were using locally administered MAC addresses. rick jones - To unsubscribe from this list: send the line unsubscribe netdev in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: Router stops routing after changing MAC Address
On Mon, 13 Mar 2006 15:27:26 -0500 linux-os \(Dick Johnson\) wrote: On Mon, 13 Mar 2006, Stephen Hemminger wrote: There still is a bug in the 3c59x driver. It doesn't include any code to handle changing the mac address. It will work if you take the device down, change address, then bring it up. But you shouldn't have to do that. Also, if the driver handles setting mac address, it could have prevented you from using a multicast address. Something like this is needed (untested, I don't have that hardware). [cut patch] Actually, it doesn't make any difference. Changing the IEEE station (physical) address is not an allowed procedure even though hooks are available in many drivers to do this. According to the IEEE 802 physical media specification, this 48-bit address must be unique and must be one of a group assigned by IEEE. Failure to follow this simple protocol can (will) cause an entire network to fail. If you don't care, then you certainly don't care about multicast bits either, basically let them set it to all ones as well. They used to allow Locally Administered Addresses. Hrm, google still finds 18,000 hits for that phrase. Is that now outlawed? Even ieee.org has hit(s) for it: http://standards.ieee.org/regauth/groupmac/tutorial.html http://en.wikipedia.org/wiki/MAC_address http://www.mynetwatchman.com/pckidiot/chap04.htm --- ~Randy You can't do anything without having to do something else first. -- Belefant's Law - To unsubscribe from this list: send the line unsubscribe netdev in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
RE: Router stops routing after changing MAC Address
On Mon, 13 Mar 2006, Greg Scott wrote: Yup. I had a situation 2 weeks ago where a customer connected a system to the Internet with an IP Address he should not have used. And the little Cisco router on the frontend dutifully recorded it in its ARP cache - forever, with no TTL! This took down their webmail for most of a day until we finally had to cycle the power on that nasty little Cisco 678. Bigger routers do it too. I've had several situations over the years where I replaced an older firewall with a newer one with the same IP Addresses. All the internal servers find it soon enough. But I've waited literally hours for the routers to finally purge their ARP caches so they would see my replacement systems - often with the customer looking over my shoulders getting more and more nervous by the minute. And sometimes the routers are not accessible - you can't cycle them even if you had permission. Consider the cases of bridged DSL service - Bst... Not! There are not any MAC addresses associated with any of the intercity links, usually not even in WANs! MAC is for Ethernet! Once you go to fiber, ATM, T-N, etc., there are no MAC addresses. That's why there are bridges and routers, you got to connect your tiny time-slot to your LAN and that first device contains the MAC address that all your other stuff talks to. where the real router could be on the other side of the country. Try calling an ISP and asking the tech on the other end to purge an ARP cache on a router. So the same IP Addresses but different MAC addresses, all you can do is wait for the passage of (lots of) time. That happened to me in my own network once. I accidently took down my email server for something like 4 hours one time when I got careless. Indeed, there is a large onus on the software doing the MAC override to make sure it does not break the required uniqueness. Just as if one were using locally administered MAC addresses. Yes. My 12:34:56 OUI scheme will work for this project but it is definitely not good for the long term. I really really hope I have to spend some money with the IEEE soon to support lots and lots of rollouts. :) - Greg Scott -Original Message- From: Rick Jones [mailto:[EMAIL PROTECTED] Sent: Monday, March 13, 2006 3:50 PM To: linux-os (Dick Johnson) Cc: Greg Scott; Chuck Ebbert; linux-kernel; netdev@vger.kernel.org; Bart Samwel; Alan Cox; Simon Mackinlay Subject: Re: Router stops routing after changing MAC Address Anyway, if the device fails, you have routers and hosts ARPing the interface, trying to establish a route anyway. But only after what may be a much longer time than the customer is willing to accept or able to configure. I know of a number of HA situations where the new device is given the old MAC just to avoid that speicific situation of ARP caches not being updated except after quite some time. Not necessarily on the end-systems, the issue can be with intermediate devices (routers). And if one has to work with static ARP entries to deal (however imperfectly) with ARP poisioning or whatnot... Indeed, there is a large onus on the software doing the MAC override to make sure it does not break the required uniqueness. Just as if one were using locally administered MAC addresses. rick jones - To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ Cheers, Dick Johnson Penguin : Linux version 2.6.15.4 on an i686 machine (5589.54 BogoMips). Warning : 98.36% of all statistics are fiction, book release in April. _ The information transmitted in this message is confidential and may be privileged. Any review, retransmission, dissemination, or other use of this information by persons or entities other than the intended recipient is prohibited. If you are not the intended recipient, please notify Analogic Corporation immediately - by replying to this message or by sending an email to [EMAIL PROTECTED] - and destroy all copies of this information, including any attachments, without reading or disclosing them. Thank you. - To unsubscribe from this list: send the line unsubscribe netdev in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
